[PATCH] virtio-blk: emit udev event when device is resized

Milos Vyletel
2013-02-21T19:11:30Z

When virtio-blk device is resized from host (using block_resize from QEMU) emit
KOBJ_CHANGE uevent to notify guest about such change. This allows user to have
custom udev rules which would take whatever action if such event occurs. As a
proof of concept I've created simple udev rule that automatically resize
filesystem on virtio-blk device.

ACTION=="change", KERNEL=="vd*", \
ENV{RESIZE}=="1", \
ENV{ID_FS_TYPE}=="ext[3-4]", \
RUN+="/sbin/resize2fs /dev/%k"
ACTION=="change", KERNEL=="vd*", \
ENV{RESIZE}=="1", \
ENV{ID_FS_TYPE}=="LVM2_member", \
RUN+="/sbin/pvresize /dev/%k"

Signed-off-by: Milos Vyletel <milos.vyletel@sde.cz>
---
drivers/block/virtio_blk.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 8ad21a2..5990382 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -539,6 +539,8 @@ static void virtblk_config_changed_work(struct work_struct *work)
struct virtio_device *vdev = vblk->vdev;
struct request_queue *q = vblk->disk->queue;
char cap_str_2[10], cap_str_10[10];
+ char event[] = "RESIZE=1";
+ char *envp[] = { event, NULL };
u64 capacity, size;

mutex_lock(&vblk->config_lock);
@@ -568,6 +570,7 @@ static void virtblk_config_changed_work(struct work_struct *work)

set_capacity(vblk->disk, capacity);
revalidate_disk(vblk->disk);
+ kobject_uevent_env(&disk_to_dev(vblk->disk)->kobj, KOBJ_CHANGE, envp);
done:
mutex_unlock(&vblk->config_lock);
}
--
1.7.1